About the throw in the towl

[Cal_stir]

consider a remote deep sand bed. a rubbermaid office garbage container or a salt bucket will do, fill with 8 inches of sugarfine reef sand, flow about 30 gph water across the top of the sand with the water about 2 in above the sand, keep it higher than your sump so you can gravity feed the water back to your sump, keep it covered and in the dark, it will take about 2 weeks for it to kick in, will reduce nitrates, i added one to my 90gal heavily stocked mixed reef and dropped my nitrates from 10 to 1, be patient and keep up the fight, ditch the sponges in the fluval. good luck